This recombinant proximal partial haplotype is a derivative of tw71 with breakpoints between D17Leh48 and D17Leh54: The proximal portion was derived from the feral mouse derived tw71haplotype and the distal portion from the C3H-Ttf chromosome. The t haplotype breakpoint is proximal to the TCR region and includes Tcd-1 and Tcd-4.